Also known as an 'inverted glass bottom boat.' This is when you encounter a girl who is so slutty that vaginal intercourse is completely out of the question. In fact, her level of whore-ness is so great that you have to worry about the disease and infestation that has made its way to her anal-cavity. One condom will not suffice with this bitch, and the risk of breaking a condom while double bagged is too great, so the only viable option is to lay a piece or saran wrap over her asshole before proceeding with insertion. This added layer of protection will help protect against most unwanted diseases.

That bitch was so dirty I had take the Great Glass Elevator all the way to the top!

Bitch ain't gonna shit right after I get off the Great Glass Elevator.